JP2804609B2 - Film coating for hard and smooth surfaces - Google Patents

Abstract

Covering a rigid or hard but pliable, smooth surface with a multilayer masking film having a smooth side and an embossed side is disclosed. The smooth side of the masking film is in direct contact with the smooth surface being covered. Adhesion of the smooth side of the masking film to the smooth surface to which it is applied is effected much like a vacuum adhesion as seen when drop of water is placed between two sheets of glass. The embossed side of the masking film forms microscopic air pockets when rolled upon itself which prevents blocking. This feature allows the non-embossed side to be made as smooth as possible without the need for an anti-blocking agent.

Description

Description: TECHNICAL FIELD The present invention relates to covering a hard but bendable and smooth surface, and more particularly comprises at least one layer of a thermoplastic adhesive-free film. Embossed with smooth sides and polished (matte emboss
ed) covering with a multilayer mask film having an embossed side comprising at least one layer of the film.

Background The function of a mask film is to form a protective cover or coating to prevent scratching, rubbing and distortion of the smooth surface to which it is applied. This protective covering or coating is necessary for shipping and during use of products having a smooth surface.

So far, conventional corona treated films and / or adhesive coated mask papers have been used for covering applications on rigid or hard but still bendable and smooth surfaces of plastics, especially polycarbonate. It has been. Polycarbonate sheets, which are typically stiff and 10 mils or thicker, are usually covered with an adhesive-backed paper. In contrast, polycarbonate films that are typically soft and of less than or equal to 10 mils are usually covered with a polyethylene film.

In the covering of a polycarbonate film, two different types of polyethylene film are used to protect both sides of the polycarbonate film. One side may be covered with a 1 mil corona treated, unembossed, low slip, low density polyethylene film. The other side may be covered with a 3 mil low density polyethylene film coated with a heat activated adhesive. Often, the polycarbonate film is sold by the manufacturer to an intermediate worker who prints on the polycarbonate film before shipping to the end user. Polyethylene film is used as a protective layer both before and after the polycarbonate sheet is printed. The 1 mil layer is usually removed just prior to printing, while the 3 mil low density layer with the adhesive applied remains on the polycarbonate throughout the printing process and is only removed by the end user. In a typical manufacturing process, both polyethylene film layers are applied simultaneously to the polycarbonate film immediately after it is extruded.
Polyethylene has a polycarbonate sheet of 100 to 2
It is applied by a nip roll when 00 ゜ F. This temperature varies with the thickness of the sheet.

In contrast, polycarbonate sheeting typically uses a paper-based mask for protection on both sides of the sheet. The paper uses a heat activated acrylic adhesive to effect its adhesion to the polycarbonate. Often, moisture from the air penetrates the paper and causes delamination between the paper and the adhesive. This causes the adhesive to remain on the polycarbonate sheet after the paper mask has been removed. Next, the adhesive must be removed from the polycarbonate with a solvent.

Various problems exist with polyethylene films currently used to cover polycarbonate films or sheets. One problem is that often different polyethylene films are used for each surface or side of the polycarbonate film, which increases film inventory and complicates product management and manufacturing methods. These increases and complications are the result of handling two types of films instead of one. Another problem is that currently used 1 mil low slip low density polyethylene films have been known to completely laminate to the polycarbonate film to which they are applied. This lamination renders the polycarbonate film essentially useless.

Another problem stems from the fact that polyethylene films are accepted from manufacturers and applied from rolls to polycarbonate films. The polyethylene film blocks on the roll and forms tight wrinkles. These hard wrinkles are problematic because they do not emerge from the polyethylene film prior to application to the polycarbonate film. These wrinkles will permanently distort the bendable surface of the polycarbonate film and render it unusable for its desired end use.

Yet another problem arises with the application of the adhesive coated 3 mil low density polyethylene film, which adheres to the polycarbonate film by use of a heat activated adhesive. This adhesive may leave residue on the polycarbonate film, which is also undesirable.

Problems also exist with adhesive paper coverings used to protect polycarbonate sheets from scratching and dents during shipping and handling. The paper with the adhesive is applied to the polycarbonate sheet at a temperature in the range of 100-320 ° F. Often, moisture from the air penetrates the paper and causes delamination. Similar problems exist with acrylics, glass, polished or painted metal, and the like, having a hard, smooth surface.

These currently used films of the related art are described in further detail below.

One mil low slip low density polyethylene film is a corona treated type of mask film. Corona treatment is the use of electrostatic discharge to increase the level of adhesion of the film. The electrostatic discharge causes surface oxidation of the film, thus making the nonpolar saturated hydrocarbon surface more chemically reactive with the polar surface, which in fact increases the level of adhesion of the nonpolar surface. Currently used mask films are not embossed and rely on a very narrow window of corona treatment to facilitate film adhesion to smooth surfaces. Corona treatment methods cannot be controlled precisely enough to ensure that production is maintained within the desired window. If the corona treatment is too little, the mask film will not adhere to smooth surfaces. If there is too much corona treatment, the mask film will stick to itself and block inside the roll, or the film will not be able to be removed by lamination to the smooth surface to which it is applied.

Corona-treated mask films have a relatively high coefficient of surface friction (greater than 0.5). These films are
It is very difficult to roll up without the inclusion of hard wrinkles that will distort a smooth surface that can be bent during application. Corona treated mask films are usually large and numerous gel and carbon specks
Which tend to dent or distort the smooth surface of the substrate to be protected.
Gels are defined as unmelted polyethylene particles that range in size from barely visible to larger than a pencil point.

As a result, these mask films show that chemical additives appear on the outer surface of the mask film (blooms).
Or moving chemical sliding (differential sli
depends on p). This prevents block formation or sticking of the mask film when the mask film is unwound from the roll, but slippage usually impairs the adhesion of the film to a smooth surface, making it less desirable as a mask film.

The 3 mil low density polyethylene film coated with the adhesive described above is an example of an adhesive mask film. These films are not embossed and affect their adhesion from the adhesive applied to the surface.
A disadvantage of this type of film is that adhesive residue often remains on smooth surfaces after removal of the mask. A solvent must be used to remove this residue. At times, the adhesive is too aggressive (bonds with great strength), which renders the mask film substantially ineffective. Like the corona treated mask, the adhesive mask film also undergoes hard wrinkles and gels.

While polished and embossed polyethylene films on one side do exist, they are used as photopolymer cover sheets. Most photopolymers have a jelly consistency. The photopolymer is applied on a polyester film base which acts as a protective carrier sheet. Next, a matte embossed polyethylene film on one side is applied in contact with the smooth non-embossed side of the exposed photopolymer surface and acts as a coversheet. The end result is a three-layer sandwich consisting of polyester film / photopolymer / frosted polyethylene, which is then wound up into rolls of various widths up to 60 inches and diameters of 10-12 inches. .

At present, photopolymers are made using two different types of polyethylene coversheet films. If the photopolymer coating is to be thin, a polished polyethylene film on one side is used with the smooth side applied to the photopolymer. If the photopolymer layer should be thicker,
A two side polished polyethylene film would be used. The difference between one side and two side polished and embossed is that in one side polished and embossed one side is smooth and the other side is polished and embossed, while In a two side polished and embossed, both sides of the film are polished and embossed. The embossing on two sides is a matte sculpture (engr) in which the molten polyethylene compressive force between the embossing roll and rubber-covered well
aved) Made by rolls. One-sided polishes are produced by compression of molten polyethylene between polished chrome and rubber rolls.

Photopolymers are used to make circuit boards. Prior to applying the photosensitive polymer to the insulating substrate, the polished and embossed polyethylene is removed from the previously described three-layer sandwich. Next, the exposed surface of the photopolymer is placed on an insulating substrate.
The opposite side of the photopolymer holds the polyester film carrier sheet. Next, the phototool is placed on top of the polyester film and then the entire multilayer substrate is exposed to a light source.

The areas of the photopolymer exposed to light cure and form a protective coating in the insulating substrate. The insulating substrate with the exposed photopolymer is then dipped in a number of chemical baths and rinsed to produce the final result printed circuit board.

SUMMARY OF THE INVENTION The present invention is an application of a multilayer mask film having a smooth side and an embossed side, wherein the smooth side is applied to a smooth surface without corona treatment or use of an adhesive. Regarding the grant.

In summary of the invention, it is disclosed that a hard or hard but bendable and smooth surface is covered by a multilayer mask film having smooth and embossed sides. The smooth side of the mask film is in direct contact with the smooth surface to be covered. Adhesion of the smooth side of the mask film to the smooth surface to which it is applied (ad
The hesion is performed roughly like a vacuum deposit as seen when a drop of water is placed between two glasses.
The embossed side of the mask film forms microscopic air pockets when rolled on itself, which prevents block formation. This feature allows the non-embossed side to be as smooth as possible without the need for an anti-blocking agent.

The current problems in the prior art are solved by achieving a constant and controlled level of adhesion, without the mask film becoming unremovable or without depositing adhesive residue. Other problems that are overcome include wrinkles that occur during block formation and winding of the film on a roll. These problems are overcome because the multilayer film has an embossed side that traps a large amount of air when it is wound on a roll. This trapping of air allows for unwrinkling of the film from the roll.

Thus, the present invention provides a mask made of a multi-layered, one-sided, glossy, embossed mask film with a hard or hard but still bendable and smooth surface, e.g.,
Lexan (Lexan) rigid polycarbonate film or plexiglass, such as ^R film (Plexiglass) ^R
It relates to applying to the surface of plastic films and sheets, including acrylic surfaces such as acrylic sheets. In addition, the multilayer one-sided polished embossed film can also be made of other plastics, glass, polished stoneware and polished or painted metal or any other smooth material. It may be applied to the surface. The multilayer mask film is embossed comprising a smooth side comprising at least one layer of a thermoplastic adhesive-free film and at least one layer of a matte embossed film. With sides. In addition, one or more core layers of the film can be inserted between the thermoplastic adhesive-free film layer and the embossed film layer.

These and other embodiments of the present invention will become apparent from the following description and the appended claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferably, the multilayer, one-sided, glossy, embossed mask film is a substrate having a hard but bendable, hard, smooth surface with a surface smoothness in the range of 0 to 150 Ra. Is given to In this regard, Ra
Is defined as the arithmetic mean height of the micropeaks to the centerline of a particular finished surface, as measured by a profilometer. This measurement is usually expressed in 10 ^-6 microinches. Preferred substrates are
It includes polycarbonate substrates, especially polycarbonate sheets having a thickness greater than 10 mils and polycarbonate films having a thickness of 10 mils or less.

In addition, the present multilayer mask films are stable when exposed to moisture, ultraviolet light, and are stable over time.

The multilayer mask film of the present invention comprises a smooth side comprising at least one layer of a thermoplastic adhesive-free film and an embossed comprising at least one layer of a polished embossed film. With the side that was made. The multilayer mask film can also have a core layer comprising a thermoplastic material interposed between the thermoplastic adhesive-free film layer and the polished embossed film layer.

The thermoplastic adhesive-free film layer used according to the invention is smooth on at least one side. This allows the multilayer mask film to be easily unwound from the roll and then applied to the substrate. The smooth side of the multilayer mask film is applied to the substrate to be covered, and it forms a vacuum adhesion. Thus, the multilayer mask film adheres firmly to the substrate, but can be removed therefrom when desired.

The multilayer mask film adheres primarily to the surface of the substrate due to intimate contact between the smooth surface of the multilayer mask film and the smooth surface of the substrate. Additional control of the adhesion of the multilayer mask film to the surface of the substrate can be achieved by controlling the desired surface tension
This can be achieved by the use of a thermoplastic adhesive-free film layer having polarity and mobility.

For best results, the smooth side of the thermoplastic adhesive-free film layer of the multilayer mask film is expected to have a smoothness in the range of about 0.25 to about 10 Ra. In addition, a film layer without thermoplastic adhesive is preferably 25
It has less than about 10 gels per square foot.

It is within the expected scope of the present invention that the thermoplastic adhesive-free film layer comprises a polyethylene (both homopolymer and copolymer) film,
Films made of polypropylene, polyvinyl chloride, nylon or polyester may also be used. For example, a thermoplastic adhesive-free film made of low-density polyethylene homopolymer is desirable, as a film with a low modulus will better match the surface to be applied. The preferred density is less than or equal to 0.945 g / cc (eg, 0.910 to 0.960), and the preferred modulus (a measure of flexial stiffness) is less than 100,000 psi. This density ratio is determined by the National Flexible Packaging As
sociation Specification) B-11, in accordance with Test Method D1505. This modulus is in accordance with the same association test method D882.

As another example, when the polyethylene film comprises a low density copolymer of ethylene and vinyl acetate, as the content of vinyl acetate increases, the film becomes softer and the sealing temperature decreases. Since this film is softer, it wets out better on smooth surfaces. In addition, by minimizing the number of gel and / or carbon stains present on the film surface, dents can be created when the film is applied to a bendable surface (dent
ing) and / or damage due to dimpling will be minimized. Accordingly, the use of such copolymers is also preferred. Still other examples of useful thermoplastic adhesive-free films include films comprising acid-modified copolymers, anhydride-modified copolymers, and acid / acrylate-modified copolymers.

The matte embossed film layer used in accordance with the present invention is embossed on at least one side, which provides a cushioning effect to the multilayer mask film. This allows the multilayer mask film to be easily unwound from the roll. The embossed film layer forms an air space between subsequent layers of the multilayer mask film when it is wound on a cylindrical roll. These air spaces prevent subsequent layers from adhering to each other and forming a solid, unusable part. Films having random shine embossing are particularly desirable for use in the present invention.

Multilayer polished embossed film layers incorporate mechanical differential slip as opposed to chemically induced differential slip. Microscopically, in one embodiment, the embossed film has a random shine rather than a patterned shine. This means that the polished embossed surface has high points or peaks containing irregular patterns that prevent the film from blocking on the roll, since there is less intimate contact between the film layers. means. Thus, the embossed film layer, once applied to the substrate, imparts anti-blocking properties to the final laminate.

The preferred embodiment uses an embossed film made of polyethylene, but any of a variety of suitable thermoplastic materials that can be easily embossed, such as polyethylene, polypropylene, polyvinyl chloride, nylon, polyester, etc. Can also be used.

The polished embossed film layer can be made of various fillers or materials that impart properties such as abrasion resistance, writeability and improved die cutting ability to the polished embossed film layer. Additives may be included. Thus, the embossed film layer also provides the required abrasion resistance in the mask film. Furthermore, the embossed surface of the embossed film layer provides a relatively rough surface that makes the surface readable. Also, with the addition of certain additives, the embossed layer has the desired opacity and / or color and surface properties that can make it readable. In certain applications, such as covering a polycarbonate sheet,
It is desirable that the mask film can be written with, for example, a No. 2 pencil. The mask film also serves as a medium for people handling the polycarbonate sheet to write instructions or indicate designs or lines for subsequent cutting equipment. For example, if a polycarbonate sheet is used for window glazing applications, the contractor can outline the desired height and width on the embossed side of the multilayer mask film. .

Additives that can be incorporated into the embossed film layer are well known and include, for example, calcium carbonate, mica and titanium dioxide. It is within the expected scope of the present invention that the embossed film layer can include any additives that can whiten and shine and thereby make the film writeable.

The ratio of the thermoplastic non-adhesive layer to the embossed layer in the multilayer mask film of the present invention varies depending on the desired properties of the multilayer mask film. It is within the expected scope of the present invention that this ratio can be varied to provide the need for abrasion resistance, stiffness, tensile strength, peel strength, and the like. The two-layer mask film of the present invention is particularly useful in end use applications where it is desired that the mask film without the adhesive be relatively flexible.

At least one core film between the thermoplastic adhesive-free film layer and the embossed film layer to help impart the desired opacity and / or color, stiffness and strength to the multilayer mask film It is also within the anticipated scope of the present invention that layers can be inserted.

The core layer used in accordance with the present invention may be a film made of any of a wide variety of thermoplastic polymeric or elastomeric materials such as polyethylene, polypropylene, polyvinyl chloride, nylon, polyester, and the like.

The multilayer mask film can be manufactured by a well-known coextrusion method. The use of the coextrusion method of film production prior to the embossing step offers important advantages.
For example, when the cost of a thermoplastic film layer is higher than the cost of an embossed film layer, significant raw material cost savings can be achieved by utilizing a coextrusion process to make a multilayer mask film.
Furthermore, by using a co-extrusion process prior to embossing, it is possible to produce a multilayer mask film consisting of separate layers of film each performing a special function. The thermoplastic adhesive-free film layer achieves adhesion to a substrate without the need for conventional adhesives and without the problems normally associated with the use of such conventional adhesives.
Adhesion of films without thermoplastic adhesives is due to the natural block-forming adhesion found in applying a very smooth surface to another smooth surface, and the polar bonding of polar polymers to polar substrates (generally ionic Bonding and in some cases by hydrogen bonding).

Any of a variety of conventional methods can be utilized to apply the multilayer mask film to the substrate and to press the applied mask film against the smooth surface of the substrate. Generally speaking, the multilayer film will be removed from the roll and applied directly to the substrate by a nip roll or similar system through which the multilayer film and the substrate are passed. In this way, the smooth side of the multilayer film is applied and pressed against the smooth side of the substrate in a single operation. If desired, the resulting object may be passed through additional compression rolls or the like. Other suitable techniques for forming the objects of the present invention will now be very apparent to those skilled in the art.

Thus, the present invention makes it possible to apply a multilayer mask film to a substrate having a smooth surface without relying on an adhesive or corona discharge or other surface treatment to achieve the required adhesion Is evident. In summary, adhesion relies primarily on intimate contact between the smooth side of the film and the smooth surface of the substrate, and to accomplish this goal, the mask film used in this operation is , Can be removed directly from the film roll. In this operation,
A matte embossed finish on one side of the mask film prevents the film from forming blocks,
And thus it is retrieved without problems like tearing, warping or wrinkling.
Thus, anti-blocking additives are unnecessary in the mask film--in fact, their presence in amounts greater than 400 ppm tends to prevent the desired adhesion between the mask film and the substrate. It will be disadvantageous because there is. For this, if if using the block formation inhibitor small amounts (up to about 400 ppm), it is desirable to use a block formation prevention additives such as SiO ₂ of diatomaceous earth.

Without departing from the inventive concept, those skilled in the art can make many other changes, modifications, and alternative implementations of the objects and techniques previously described herein. Will be able to. Therefore, it should be clearly understood that the objects and methods described in the foregoing description are merely illustrative and are not intended to limit the scope of the invention as defined in the appended claims. .

 The main features and aspects of the present invention are as follows.

1) An object comprising a substrate having a rigid or hard, smooth surface and having a multilayer mask film attached thereto, wherein the multilayer mask film is free of a thermoplastic adhesive having a smooth outer surface. A multilayer mask comprising at least one outer layer of the film and at least one outer layer of the film having a rough outer side, wherein the smooth side of the multilayer mask film is attached to the smooth surface of the substrate, wherein the multilayer mask The film is an object detachably attached to the surface of the substrate.

2) Due to the close contact between the smooth surface of the multilayer mask film and the smooth surface of the substrate and due to the surface tension, polarity and mobility of the film without thermoplastic adhesive, the multilayer mask film is 2. The object according to 1 above, which is detachably attached.

3) The object according to 1 above, wherein the substrate is made of polycarbonate.

4) The object of 1 above, wherein the substrate has a thickness greater than 10 mils.

5) The object of 1 above, wherein the substrate has a thickness of 10 mils or less.

6) The article of claim 1 wherein the thermoplastic adhesive-free film layer comprises polyethylene.

7) The article of claim 1 wherein the thermoplastic adhesive-free film layer comprises a low density polyethylene copolymer.

8) The thermoplastic adhesive-free film layer is an acid-modified copolymer, an anhydride-modified copolymer or an acid /
An object according to claim 1 consisting of an acrylate-modified copolymer.

9) The method according to 1) above, wherein the coarse film layer is a thermoplastic film.
An object according to.

10) The object of 1 above, wherein the coarse film layer is made of polyethylene, polypropylene, polyvinyl chloride, nylon or polyester.

11) The object of 1 above, wherein the rough film layer comprises additives to impart abrasion resistance, writability or die cutting ability.

12) The multilayer mask film as described in 1 above, wherein the multilayer mask film comprises one or more core layers of the film interposed between the thermoplastic adhesive-free film layer and the coarse film layer.
An object according to.

13) The above-mentioned 12 wherein the core film layer is a thermoplastic film.
An object according to.

14) The substrate has a thickness greater than 10 mils, and the multi-layer film attached thereto comprises a thermoplastic polyethylene, a low density polyethylene copolymer, an acid-modified copolymer, an anhydride-modified copolymer or an acid / acrylate modifier. An article according to claim 1, comprising an adhesive-free film layer of the textured copolymer and a coarse thermoplastic film layer.

15) The substrate has a thickness of 10 mils or less, and the multilayer film attached thereto is a thermoplastic polyethylene, a low density polyethylene copolymer, an acid modified copolymer, an anhydride modified copolymer or an acid. An object according to claim 1 comprising an adhesive-free / acrylate-modified copolymer-free film layer and a coarse thermoplastic film layer.

16) The substrate has a thickness greater than 10 mils, and the multi-layer film attached thereto comprises a thermoplastic adhesive-free film layer, a coarse film layer, and a thermoplastic adhesive-free film layer and a coarse film. An object according to claim 1, comprising a layer comprising a core film inserted between the layer and the layer.

17) The substrate has a thickness of 10 mils or less, and the multilayer film attached thereto comprises a thermoplastic adhesive-free film layer, a coarse film layer, and a thermoplastic adhesive-free film layer. The object of claim 1, comprising a core film layer interposed between the coarse film layer.

18) A method of applying a masking or protective film to a substrate having a smooth surface, comprising applying at least one outer layer of a thermoplastic adhesive-free film having a smooth outer surface and a film having a rougher outer surface. Comprising at least one outer layer, substantially free of antiblocking additives, and the smooth side of the multilayer mask film unwinds the multilayer mask film without corona discharge or similar surface treatment; and Unwind the multilayer mask film and apply the smooth side of the multilayer mask film directly to the smooth surface of the substrate, and press the multilayer mask film against the substrate to allow adhesion between them without using any adhesive. A method characterized by achieving.

19) A method of coating a hard or hard but bendable smooth surface, comprising at least one of a thermoplastic glueless film having a smooth outer surface on a hard but bendable smooth surface. A multi-layer mask film comprising an outer layer and at least one layer of a film having a rough outer side is provided such that the smooth side of the multi-layer mask film is in direct contact with the hard but bendable smooth surface. And pressing the smooth side of the multilayer mask film against a hard but bendable smooth surface.

20) The coarse film layer is polyethylene, polypropylene,
20. The method according to 19 above, comprising polyvinyl chloride, nylon or polyester.

21) The method of claim 19, wherein the thermoplastic adhesive-free film layer of the multilayer mask film is a low density ethylene copolymer film having a density in the range of 0.910 to 0.960 g / cc.

22) The method of claim 19, wherein the thermoplastic adhesive-free film has less than 10 gels per 25 square feet.

23) The method according to 19 above, wherein the application of the multilayer mask film is from a roll, and the multilayer mask film easily comes out of the roll due to trapping of air in micro pockets.

24) The method according to 19 above, wherein the coarse film layer has a random shine embossing.

25) Multi-layer mask film is manufactured by co-extrusion method,
20. The method according to 19 above.

26) The rough film layer comprises a filler to impart abrasion resistance, writability or improved die cutting capability.
19. The method according to 19.

27) The method of the above 19, wherein the rough film layer once applied to the substrate gives the multilayer mask film anti-blocking properties.
The method described in.

28) The method according to 19 above, wherein the multilayer mask film is stable when exposed to moisture.

29) The method according to 19 above, wherein the multilayer mask film is stable when exposed to ultraviolet light.

30) The multilayer mask film is stable over time.
The method described in.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-37930 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B32B 1/00-35/00

Claims (3)

(57) [Claims] 1. An object comprising a substrate having a hard or hard smooth surface and having a multilayer mask film attached thereto, wherein the multilayer mask film is a thermoplastic adhesive having a smooth outer surface. Comprising at least one outer layer of a film without the agent and at least one outer layer of a film having a rough outer side, wherein the smooth side of the multilayer mask film is attached to the smooth surface of the substrate, The multilayer mask film is an object that is detachably attached to the surface of the substrate. 2. An anti-blocking additive comprising at least one outer layer of a thermoplastic adhesive-free film having a smooth outer surface and at least one outer layer of a film having a rough outer surface. The smooth side of the multilayer mask film is substantially free and the smooth side of the multilayer mask film is uncorona discharge or similar surface treated, and the smooth side of the multilayer mask film is unwound from the substrate while unwinding the multilayer mask film. For applying a mask to a substrate having a smooth surface, characterized in that it is applied directly to a smooth surface and the multilayer mask film is pressed against the substrate to achieve adhesion therebetween without using any adhesive. A method of providing a protective film. 3. A method according to claim 1, wherein the at least one outer layer of the thermoplastic adhesive-free film having a smooth outer surface and the at least one layer of the film having a rough outer surface are provided on a hard but bendable smooth surface. A multilayer mask film comprising: applying a smooth side of the multilayer mask film in direct contact with a rigid but bendable smooth surface; and a multilayer mask against the rigid but bendable smooth surface. A method of coating a hard or hard but bendable smooth surface, comprising the step of pressing the smooth side of the film.